The earlier an adolescent initiates substance use, the greater the risk of long-range problems. This association persists despite changes in national substance use rates over time, indicating its stability and viability as a target for prevention. At the same time, parent monitoring of youth behavior tends to decrease during the adolescent years, creating a source of risk for the early onset of substance use. Thus, programs that foster parenting behaviors and family relationships that are protective in helping youth to avoid substance abuse are an important area of continuing research. To date, most of the research has been conducted on universal prevention programs based in schools. Some selective prevention programs with high risk groups have also been conducted in schools. Only rarely do these universal or selective programs involve parents. The Family Check-Up (FCU) is an exception to this trend as it is a selective intervention program that focuses on parents. A unique strength of the FCU is that feedback is individualized and tailored to specific parenting skills as they typically pertain to an identified adolescent in the family. Our group has found that the Family Check-Up had better effects on reducing alcohol use in teens presenting to an Emergency Department as alcohol-positive at 6 month follow-up than an individual motivational intervention. In this application, which is submitted in response to PA-07-406, Screening and Brief Interventions in Underage and Young Adult Alcohol Populations, we propose to evaluate the efficacy of the FCU when applied to both an adolescent Identified Patient (IP) and a sibling close in age. Our rationale for including a sibling close in age derives from a strong empirical base which has shown that: 1) sibling resemblance for alcohol use is high and environmental factors shared by siblings account for substantial portions of variance in adolescent alcohol use; and 2) specific interactional dynamics of the sibling relationship (collusion) are related to teen alcohol use. In order to determine whether other types of family-based interventions might be just as helpful as the FCU, efficacy of the sibling-enhanced FCU will be compared to a parenting psychoeducational program, Family Matters (FM). The major goal of this application is to evaluate the efficacy of a sibling-enhanced FCU in reducing alcohol and other drug use in an adolescent IP presenting with an alcohol-related event and a sibling close in age. Changes in parental monitoring and other adolescent health risk behaviors will also be measured over a 1-year period.